Ultra short wave apparatus



Oct 14, 19 J. w. CONKLIN ULTRA SHORT WAVE APPARATUS Filed Nov. 17, 1959Smim 2 INVENTOR. JAMES W CONKLIN A TTORNEY.

Patented Oct. 14, 1941 ULTRA SHORT WANE APPARATUS James W. Conklin,Audubon, N. J., assignor to Radio Corporation of America, a corporationof Delaware Application November 17, 1939, Serial No. 304,889

13 Claims.

The present invention relates to ultra short wave electron dischargedevice circuits, and particularly to resonant line controlled equipment.

An object of the present invention is to pro vide an improved mechanicaldesign for an electron discharge device associated with a resonant linecircuit in which the lengths of the connections from the electrondischarge device to the resonant lin are minimized, and made adjustableover the length of the resonant line.

Another object is to provide an improved mounting for an electrondischarge device associated with a coaxial line resonator in which thedischarge device is positioned between the conductors of the resonator,and means are provided for adjmting the position of the dischargedevice.

A further object is to provide an audio frequency generator composed ofa pair of ultra high frequency stabilized oscillators whose outputs arecombined in a detector unit to provide an audio beat signal.

A feature of the invention lies in the use of a coaxial or concentricline resonator having an electron discharge device mounted between theconductors of the resonator with leads of minimum length arranged forconnection to the most suitable points on the resonator. A further features resides in the manner of mounting the electron discharge device ona movable tubular support, there being slidable spring contactsassociated with certain electrodes of the discharge device forconnection with the conductors of the concentric line resonator.

Other objects and features will appear from a reading of the followingdescription given in conjunction with a drawing whose single figureillustrates a beat frequency generator composed of a pair of coaxialresonant line controlled os cillators beating together to form an audiobeat signal.

Referring more particularly to the drawing, there are shown twoidentical ultra high fre-- quency oscillator circuits, each comprisingan evacuated electron discharge device I positioned between conductors2, 3 of a concentric line resonator employed for stabilizing thefrequency of the oscillator. The line resonator is a high Q line (lowloss) having an outer conductor 3 and an inner conductor 2, bothconnected together at one end by a metallic end plate 4. Attached to thefree end of each inner conductor 2 is a corrugated metallic bellows 5mechanicallylinked to a low temperature coeilicient Invar rod 6 formaintaining th overall length of the inner conductor 2 substantiallyconstant against tempera ture variations. Slight adjustments in overalllength of the inner conductor can be made by movement of the knurledscrew 7. This type of concentric resonant line has an effectiveelectrical lengthof one-quarter wave at the. operating frequency, and isnow known in the art, reference being made to United States Patent No.2,108,895, granted February 22, 1938, to Fred H. Kroger and UnitedStates Patent No. 2,103,515, granted December 28, 1937, to James W.Conklin et al.

The vacuum tube l of ach oscillator circuit is mounted between the innerand outer conductors of the resonant line 2, 3 and has its anode andgrid directly connected by slidable flexible spring contacts 8 tometallic bars or plates 9, in turn insulatingly mounted on theconductors of the line resonator by virtue of insulating spacers til, asshown. The vacuum tube is preferably of the small acorn type, such asthe RCA Typ 955 Acorn triode, and is supported at one end of a slidablecopper tube ll positioned half Way between the inner and outerconductors of the line resonator. The cathode and filament leads ex tendthrough the interior of the tubing II and are brought out at thshort-circuited end of the resonant line. The cathode is grounded to thesupporting tube It and end plate 4, as shown, while the filament leadsare by-passed to ground for radio frequency currents through condensersl2, 12. The grid and anode electrodes of the vacuum tube I are suitablypolarized by connections which extend to the bars or plates 9, the gridelectrode obtaining its bias by Way of grid lead l3 while the anodeelectrode obtains a positive polarizing potential through the filter M.It should be observed that the leads between the grid and anodeelectrodes of the vacuum tubes and the conductors of the resonant linesare of minimum length and hence of minimum inductance. The copper tubingI I which suports the vacuum tube l is slidable through end plate 4 andthus can move the vacuum tube and associated leads and flexible contactsprings to any desired suitable location over the length of bars 9. Ifthe vacuum tube is connected-near end plate 4, maximum frequencystability will be obtained but the circuit load on the electrondischarge device will be maximum, and may be sufcient to prevent thevacuum tube from oscillating. Therefore, the actual adjustment is acompromise between reliable vacuum tube performance and maximumfrequency stability.

Each oscillator can be compared to a Hartley circuit wherein the gridandanode are connected to opposite ends of an inductance coil throughcondensers, and the cathode to the center of the inductance coil.

Filters M are of the three section type and are designed tosubstantially prevent radio frequency energy in the oscillator circuitsfrom entering the power supply circuit i5 and the detector unit [6 overthe connections extending thereto. The filters reduce radio frequencycurrents in the leads external of the line resonator to prevent as faras possible all undesired coupling between the two oscillator units. Apair of resistors I! in series with the anode leads serve to reduce thevoltage on the anodes of the vacuum tubes and also protect the vacuumtubes in case of tube failure.

The detector unit I6 is an RCA Type 954 Acorn pentode operating as abiased detector tube and contains a simple parallel tuned circuit l8.This detector unit is completely enclosed in a metallic shield I9 shownin dotted lines. 20, a portion of which extends outside of the shieldI9, is employed to couple the tuned circuit I8 to the two oscillatorcircuits, and this is achieved by virtue of leakage radiation from theresonators. leakage from the oscillators, then holes may be provided inthe outer conductors of the resonator, in order to obtain suflicientexternal field to operate the detector unit IS.

The two oscillators I, l and the detector unit are connected by means ofshielded plug-in cables to the common power supply I5 to provide thenecessary voltages for the vacuum tube electrodes. This power supplycircuit is of the conventional type which may be plugged into a 110volt, cycle supply.

The output of detector unit It serves to excite a power amplifiercircuit 2| and associated loud speaker 22.

In operation, the two oscillators are adjusted by means of screws 1 toproduce slightly different frequencies so as to produce an audiofrequency beat note in the detector unit. The direct current in theanode circuit of the detector will be very small or zero until the radiofrequency potential is applied to the control grid, after which thecurrent flows in the detector approximately proportional to theamplitude of the radio frequency current.

In one embodiment successfully tried out in practice, the oscillators'functioned at a frequency of about 300 megacycles, although it will beappreciated that there would be less load on the vacuum tubes and higherfrequency stability at lower frequencies.

What is claimed is:

1. The combination with a tuned circuit in the form of a coaxial lineresonator having an outer conductor and a coaxial inner conductor, of amulti electrode electron discharge device located between the conductorsof said resonator, a connection coupling one electrode of said device tothe inner surface of said outer conductor and a connection couplinganother electrode of said device to the inner conductor, whereby thewiring between said electrodes and said resonator are reduced to aminimum, and means for adjusting the position of said device andassociated connections over a portion of the length of said lineresonator.

2. In combination, a tuned circuit in the form of a coaxial lineresonator having an outer conductor and a coaxial inner conductor, ametallic plate coupling said conductors together at substantially e we;a meta l c o w l r m An antenna rod 1 Where the filters l4 prevent anyductor passing through said plate and positioned half-way between saidouter and inner conductors, said tubular conductor being movable throughsaid plate in the direction of the length of said conductors, amulti-electrode electron discharge device located within said resonatorand mounted on one end of said tubular conductor and movable therewith,and connections coupling certain electrodes of said device to theconductors of said resonator in the interior thereof.

3. In combination, a tuned circuit in the form of a coaxial lineresonator having an outer conductor and a coaxial inner conductor, ametallic plate coupling said conductors together at substantially oneend, a metallic hollow tubular conductor passing through said plate andpositioned half-way between said outer and inner conductors, saidtubular conductor being movable through said plate in the direction ofthe length of said conductors, a multi-electrode electron dischargedevice located within said resonator and mounted on one end of saidtubular conductor and movable therewith, and connections includingflexible contact springs coupling certain electrodes of said device tothe conductors of said resonator in the interior thereof.

4. In combination, a tuned circuit in the form of a coaxial lineresonator having an outer conductor and a coaxial inner conductor, ametallic plate insulatingly positioned on the interior surface of saidouter conductor, and a metallic plate insulatingly positioned on saidinner conductor, both of said plates facing each other and extendingover at least a small portion of the length of said resonator, anelectron discharge device located in the space between said plates, aconnection from one electrode of said device to one of said plates, anda connection from another electrode of said device to the other of saidplates, whereby the Wiring between said electrodes and the conductors ofsaid resonator are a minimum.

5. In combination, a tuned circuit in the form of a coaxial lineresonator having an outer conductor and a coaxial inner conductor, ametallic plate insulatingly positioned on the interior surface of saidouter conductor, and a metallic plate insulatingly positioned on saidinner conductor, both of said plates facing each other and extendingover at least a small portion of the length of said resonator, anelectron discharge device located in the space between said plates, aconnection from one electrode of said device to one of said plates, anda connection from another electrode of said device to the other of saidplates,

' whereby the wiring between said electrodes and the conductors of saidresonator are a minimum, and a metallic tube extending parallel to saidconductors of said resonator and in the interior of said resonator andsupporting at one end said device.

6. In combination, a tuned circuit in the form of a coaxial lineresonator having an outer conductor and a coaxial inner conductor, ametallic plate insulatingly positioned on the interior surface of saidouter conductor, and a metallic plate insulatingly positioned on saidinner conductor, both of said plates facing each other and extendingover at least a small portion of the length of said resonator, anelectron discharge device located in the space between said plates, aconnection including a flexible contact spring from one electrod of saiddevice to one of said plates, and a connection including a flexiblecontact spring from another electrode of said device to the other ofsaid plates, whereby the wiring between said electrodes and theconductors of said resonator are a minimum, and a metallic tubeextending parallel to said conductors in the interior of said resonatorand supporting at one end said device, said metallic tube being movablelengthwise for adjusting the position of said device and associatedelectrode connections over the lengths of said plate.

7. Th combination with a tuned circuit in the form of a coaxial lineresonator having an outer conductor and a coaxial inner conductor, of amulti-electrode electron discharge device located between the conductorsof said resonator, a connection including a flexible contact springcoupling one electrode of said device to the inner surface of said outerconductor and a connection also including a flexible contact springcoupling another electrode of said device to the inner conductor,whereby the wiring between said electrodes andsaid resonator are reducedto a minimum, and means for adjusting the position of said device andcontact springs over a portion of the length of said line resonator.

8. Apparatus in accordance with claim 5, characterized in this that saidelectron discharge device has a cathode and a heater, and there areconnections for said cathode and heater which extend within the metallictube supporting said electron device.

9. In combination, a resonant circuit having a pair of conductivesurfaces separated solely by space, a metallic plate insulatinglypositioned on one of said pair of surfaces, and a metallic plateinsulatingly positioned on the other of said pair of surfaces, both ofsaid plates facing each other, an electron discharge device located inthe space between said plates and having a cathode and a pair of coldelectrodes, a connection from one of said cold electrodes to one of saidplates, and a connection from the other cold electrode to the other ofsaid plates, whereby the wiring between said electrodes and the pair ofsurfaces of said resonant circuit are a minimum, a hollow tubularconductor entering the space between said conductive surfaces, and aconnection from said cathode extending through the interior of saidhollow tubular conductor externally of said resonant circuit.

10. In combination, a resonant circuit having a pair of conductivesurfaces separated solely by space, a metallic plate insulatinglypositioned on one of said pair of surfaces to form a condenser, and ametallic plate insulatingly positioned on the other of said pair ofsurfaces to form a condenser,

both of said plates facing each other, an electron discharge devicelocated in the space between said plates and having a cathod and a pairof cold electrodes, a connection from one of said cold electrodes to oneof said plates, and a connection from the other cold electrode to theother of said plates, whereby the wiring between said electrodes and thepair of surfaces of said resonant circuit are a minimum, a hollowtubular conductor entering the space between said conductive surfaces,and heater leads for said cathode extending through the interior of saidhollow tubular conductor to a source of heater energy located externallyof said resonant circuit.

11. In combination, a resonant circuit having a pair of conductivesurfaces separated solely by space, a metallic plate insulatinglypositioned on one of said pair of surfaces, and a metallic plateinsulatingly positioned on the other of said pair of surfaces, both ofsaid plates facing each other, an electron discharge device located inthe space between said plates, a connection from one electrode of saiddevice to one of said plates, and a connection from another electrode ofsaid device to the other of said plates, whereby the wiring between saidelectrodes and the pair of surfaces of said resonant circuit are aminimum, a hollow tubular conductor entering the space between saidconductive surfaces, and a connection from a third electrode of saiddevice extending through the interior of said hollow tubuular conductorexternally of said resonant circuit.

12. Apparatus in accordance with claim 9, characterized in this thatsaid tubular conductor is metal.

13. In combination, a resonant circuit having a pair of conductivesurfaces separated solely by space, a metallic plate insulatinglypositioned on one of said pair of surfaces, and a metallic plateinsulatingly positioned on the other of said pair of surfaces, both ofsaid plates facing each other, an electron discharge device located inthe space between said plates and having a cathode and a pair of coldelectrodes, a connection from one of said cold electrodes to one of saidplates, and a connection from the other cold electrode to the other ofsaid plates, whereby the wiring between said electrodes and the pair ofsurfaces of said resonant circuit are substantially a minimum, and meanscoupling said cathode to a point of fixed radio frequency potential.

JAMES W. CONKLIN.

